Conventionally, an electrostatic chuck apparatus is used to, for example, retain a wafer in a processing apparatus. As an example of the electrostatic chuck apparatus, there is an electrostatic chuck apparatus that adheres an electrostatic chuck to a pedestal by using a resin adhesive agent. The pedestal has high thermal conductivity, so that the temperature of a wafer to be retained by the electrostatic chuck can be prevented from increasing.
However, the resin adhesive agent is susceptible to corrosion by a process gas having high corrosiveness. Therefore, in a case where the electrostatic chuck apparatus is used in an environment using a process gas having high corrosiveness (e.g., inside a plasma etching apparatus using a process gas having high corrosiveness) for a long time, the resin adhesive agent may corrode.
In a case where corrosion of the adhesive agent occurs, the bonding strength between the pedestal and the electrostatic chuck may deteriorate, and a shape of a ceramic substrate included in the electrostatic chuck may change. Ina case where a cooling gas is supplied between the electrostatic chuck and the wafer, the change of the shape of the ceramic substrate may cause the gas to leak and prevent gas from being sufficiently supplied to a back surface of the wafer. This may lead to a case where the wafer cannot be sufficiently cooled or a case where the atmosphere inside the processing apparatus is degraded. Further, in a case where the adhesive surface between the electrostatic chuck and the pedestal is corroded, heat transfer between the electrostatic chuck and the pedestal cannot be sufficiently achieved at the adhesive surface. This lead to problems such as degradation of the distribution of the temperature of the wafer.
For example, Japanese Laid-Open Patent Publication No. 2003-179129 discloses an electrostatic chuck apparatus for preventing corrosion at an adhesive part. The electrostatic chuck apparatus has an electrostatic chuck that includes a side surface having a ring-shaped concave part and/or a convex part formed along an outer periphery of the electrostatic chuck, and an insulating ring that engages the concave part and/or the convex part.
However, corrosion of the adhesive agent cannot be sufficiently prevented even with the electrostatic chuck apparatus disclosed in Japanese Laid-Open Patent Publication No. 2003-179129. As illustrated in FIG. 1A, in a case where there is a space 15 between an insulating ring 14 and an electrostatic chuck 12 in an environment using a process gas having high corrosiveness (e.g., inside a plasma etching apparatus), the process gas may enter the space 15 and cause corrosion of a bonding layer 13.
For example, in a case of periodically cleaning the inside of a processing chamber, the cleaning may be performed in a state where a wafer 16 is not retained on the electrostatic chuck 12 (see FIG. 1B) or in a state where the wafer 16 is lifted. In this case, the process gas is even more likely to enter the space 15 and cause corrosion of the bonding layer 13, compared to the case illustrated in FIG. 1A.
Further, because the electrostatic chuck apparatus disclosed in Japanese Laid-Open Patent Publication No. 2003-179129 has the insulating ring 14 provided along the outer periphery of the electrostatic chuck, the size of the insulating ring 14 may increase depending on the size of the electrostatic chuck. This leads to an increase of the entire size of the electrostatic chuck apparatus as well as the weight of the electrostatic chuck apparatus.